EP0742658B1

EP0742658B1 - Dynamic channel assignment for data transmitted via cable television channels

Info

Publication number: EP0742658B1
Application number: EP96303091A
Authority: EP
Inventors: Venkata Chalapathi Majeti; Mark Meir Rochkind
Original assignee: AT&T Corp; AT&T IPM Corp
Current assignee: AT&T Corp
Priority date: 1995-05-08
Filing date: 1996-05-01
Publication date: 2005-02-23
Anticipated expiration: 2016-05-01
Also published as: DE69634375D1; JP3486294B2; US5675732A; EP0742658A3; EP0742658A2; CA2173303A1; JPH08316992A; CA2173303C; DE69634375T2

Description

Technical Field

The invention relates to data communication and more particularly to data communication via cable television systems.

Description of the Prior Art

One known high-speed data communication system capable of data rates of 10 Mega bits per second is the asymmetric system of Moura et al. described in U.S. Patent No. 5,347, 304. The system of Moura et al. transmits digital information in the form of packets to any remote location such as a home, school, or office using standard cable television practices and components. FIG. 1 shows such a system 100 that has an end user PC 104 with an IEEE 802.2 interface 106 connected to the Remote Link Adapter (RLA) 108 via coaxial cable 110. RLA 108 acts as a router for the PC 104. The RLA 108 supports a coaxial connection 112 for downstream data delivery to PC 104 and a telephone modem connection 114 for upstream user signaling and control. As shown in FIG. 1, data packets addressed to PC 104 are routed to a network router 120, where the data packets are transformed into a 6 MHz RF carrier signal compatible with broadcast television standards. The data is then distributed over a conventional cable network. However, this known asymmetric system 100 is for a single user system and a data rate that did not require more than a single cable channel having a maximum of 6 Mhz.
The system of Moura et al is not readily expandable to provide service to multiple users both from a bandwidth point of view and from an address point of view. Further, simply providing each of multiple users with a channel assignment and a unique internet protocol address typically leads to needless duplication of routing and related hardware and inefficient allocation of bandwidth among multiple channels. If a channel is actually assigned more users than it can service at one time, at a heavy usage time a user that is pre-assigned to one channel may not be allowed access to that channel because of usage, while a second channel may actually be under utilized. Thus, there is a need in the art for a multiple user high speed data system that does not require duplication of hardware and which can load share among multiple channels to use bandwidth efficiently.
Apparatus and a method according to the invention are as set out in the independent claims. Preferred forms are set out in the dependent claims.

Summary of the Invention

Briefly stated, the problems of the prior art are solved and the state of the art advanced by providing a system delivering data services which efficiently uses channel bandwidth across several channels, such as cable television channels. The system dynamically assigns users to empty bandwidth of two or more channels. The system has a network for communicating data packets according to internet protocol to a local network unit. The local network unit is connected to this internet protocol network and operates as a bridge from internet protocol to a group of frequency division multiplexed channels that are compatible with television program distribution. This local network unit bridges the data packets from the network to the channels. A number of single user data units are connected to this local network unit via one of the channels, each is connected in order to receive its respective data packets. Each of these single user data units has a unique address to distinguish it from the other single user data units. The system also has one or more data service provider units, each of which is connected to the internet protocol network for transmitting data packets to the local network unit and the channels for distribution to respective single user data units requesting data services. Each of these data service provider units is also connected to each single-user-data-unit-to-which-it-transmits-data-packets via another communication path for controlling the transmission of data packets. Further, the system has a bandwidth manager that is connected to the data service provider units and the local network unit via the internet protocol network. This bandwidth manager keeps a dynamic record of an amount of bandwidth used of each of the channels and assigns any new bandwidth allocation for data services to the channel which has the most available bandwidth remaining.
In another aspect of the invention, the problems of the prior art are solved and an advancement in the art is achieved by providing a method for delivering data services efficiently. The method includes the steps of: communicating data packets according to internet protocol via a first network; receiving the data packets from the first network and multiplexing the data packets by a local network unit onto a second network having a plurality of channels; receiving the data packets by a plurality of single user data units that are connected to the second network upon one of the plurality of channels, each of the single user data units having a unique address; distributing data packets from a plurality of data service provider units to the single user data units via the first network, the local network unit, the second network and the plurality of channels of the second network; controlling the distributing of data packets from each of the data service provider units to each single user data unit to which it transmits said data packets via another communication path outside of the first network; and dynamically managing these channels with a bandwidth manager that is connected to the plurality of data service provider units and the local network unit via the network. The bandwidth manager keeps a dynamic record of each amount of bandwidth used of each of the plurality of channels and uses this record to fulfill any new bandwidth request for data services to the channel which has the most bandwidth available.

Brief Description of the Drawing

FIG. 1 is a block diagram of a known data delivery system.
FIG. 2 is a block diagram of a data delivery system with dynamic channel assignment and management according to the present invention.

Detailed Description

Referring now to FIG. 2, a data delivery system 200 is shown. The system 200 connects data service providers 300₁-300_N to single user data units 230₁-230_m, which are end users. The data service providers 300₁-300_N may be providing online data services such as text, stock quotes, multimedia, video games, etc.
Data service providers 300₁-300_n, are connected to an internet protocol (IP) network 204 and can send and receive data packets thereby. Also connected to internet protocol network 204 is a multiplexing platform 210. Multiplexing platform 210 receives data packets in internet protocol and multiplexes and modulates them into one of a number of frequency channels. In one embodiment of the present invention, the multiplexing platform 210 modulates the data packets received from the IP network 204 into one of two or more 6 megahertz wide television compatible channels. The modulation used is compatible with existing television signal equipment, so the modulated data packets are distributed using the same equipment as cable or free space broadcast television signals. Three channels 212, 213, and 214 are shown, but any number greater than two is considered within the scope of the invention. Channels 212, 213, and 214 are transported via a common media 216, such as community antenna television (CATV) cable, optical fiber, or even free space.
Common media 216 is connected to remote link adapters (RLAs)220₁-220_M, which may be independent units such as 220₁, or may be part of another unit. Each RLA 220₁-220_M demodulates and demultiplexes the data packets on one of the channels 212, 213, or 214 to which it is tuned. Each RLA 220₁ -220_m is channel agile and may be tuned in response to a signal from the had end bandwith manager 240 to any channel 212, 213 or 214. RLA 220₁ converts the demodulated data packets into a IEEE 802.2 protocol data packets and forwards the data packets to the single user data unit 230₁, which may be a data terminal, a work station, a personal computer, or some other type of data equipment. The RLAs 220₂-220_M are part of single user data units 230₂-230_M, thus RLAs 220₂-220_M demodulate and demultiplex data packets on their respective channels and transmit these packets directly to single user data units 230₂-230_M via respective internal buses. Different RLAs may be dynamically configured to use different amounts of channel bandwidth, e.g., 150 kbps, 300 kbps, etc. Once the data packets reach their respective single user data units 230₁-230_M, the data packets may be treated as any other data packet. So, to a great extent, the intermediate stages between data service providers 300₁-300_N and single user data units 230₁-230_M are transparent to the data packets.
The distribution of data packets from the data services providers 300₁-300_N to single user data units 230₁-230_M through multiplexer platform unit 210 is primarily one way, which means that a second path of some type must exist in order to have some type of control on the packet data, assuming it is not a pure broadcast arrangement such as commercial television.
Each single user data unit 230₁-230_M also has a connection available 232₁-232_M to any one of the data providers 300₁-300_N via a narrow bandwidth data line such as a telephone line or a back channel line of some cable television distribution systems. The single user data units 230₁-230_M communicate over the narrowband line using a modem or some other suitable low data rate device. The connections 232₁-232_M when established are two way data paths, so establishment of a connection and requests for data can be forwarded and acknowledged.
Also part of the system 200 is a bandwidth manager 240. Bandwidth manager 240 is connected to data service providers 300₁-300_N via IP network 204. Bandwidth manager 240 is also connected to multiplexing platform unit 210 via IP network 204. Bandwidth manager 240 is an important part of managing the bandwidth of the connections. Bandwidth manager 240 may be a built-in function of the multiplexing platform 210, or remain independent as shown in FIG. 2 in order to manage a distributed architecture with several multiplexing platforms in a given region (not shown). The role and rationale for the bandwidth manager 240 is derived from an assumption that the current data service providers will evolve into more multimedia services. If one of the data service providers 300₁-300_N is able to respond to a request from a specific user, the request is forwarded to the bandwidth manager 240 requesting bandwidth for high speed distribution to the requesting user. The request may be for date to be delivered at one of a set of rates, e.g., 150 kbps, 300 kbps, 1.5 mega bps, etc.
The multiplexing platform 210 operates all of the supported channels 212, 213, 214 as part of one sub-network address. In order to determine how data from data service providers 300₁-300_N is routed to a channel modulator, the bandwidth manager 240 collects traffic and utilization statistics for each channel. The bandwidth manager 240 also receive notifications from the data service providers when a user session terminates so that the assigned bandwidth of that session can be reassigned. The assignment of a channel at data service request and negotiation time and the release of that channel after the distribution of the requested data is distributed in the present invention is called dynamic channel assignment.
The are three key steps involved in providing dynamic channel assignment. The first step in achieving dynamic channel assignment is to manage all multiplexing platform channels as part of one subnetwork. Additionally, each of the single user data units 220₁-220_M may be dynamically tuned to any of the available channels. In order to send incoming data on any given channel 212-214 to any given single user data unit 220₁-220_M, the multiplexing platform 210 needs to maintain an active routing table that specifies each single user data unit destination address and the corresponding channel modulator employed. This ensures that data destined to single user data units is transmitted on an appropriate channel.
The next step to achieving dynamic channel assignment is to use a routing table to direct incoming data to appropriate single user data unit address. Management of routing table is tightly coupled to the single user data units that are actively involved in receiving data over common media 216. When a new single user data unit 230₁-230_M initiates a session requiring channel bandwidth (say on Channel 30) the utilization statistics of the bandwidth manager routing table would be adjusted by an amount of channel bandwidth requested and allocated. Similarly, when a session is terminated, the utilization statistics representing the channel of the terminated session is adjusted by the amount of channel bandwidth released. Channel assignment for each user request is provided by bandwidth manager as part of the service negotiation process. Assignments are based on channel utilization statistics at the time that a new request is processed. Use of service negotiation process to increment and decrement active user statistics for each channel is a departure from current known systems, which instead use pre-assigned channels.
The third step to providing dynamic channel assignment is distinguishing active single user data units from all other subscribers in a given serving area. This is accomplished during the service negotiation process just after a single user data unit of units 230₁-230_M completes a narrowband connection, if wide band distribution services are necessary. Channel assignments are communicated from the bandwidth manager 240 back to each single user data unit either via the narrowband connection thereto, or via broadcast on the respective default channel of the RLA of the single user data unit. This information is maintained in the bandwidth manager 240.
The important part of managing all channels as part of one sub-network is what distinguishes the role of the multiplexing platform 210 from a generic IP router. In the case of a generic IP router (not shown), each channel modulator having an independent sub network address simplifies how incoming data packets are routed from the IP network to the channel modulator and to an active single user data unit. Without violating any general networking principles, a generic router with a built-in scheme to balance load across all of the supported channels could be built. However, the natural evolution of data service distribution leads to requirements for multiplexing platform 210 and bandwidth manager 240 beyond that of a generic router. These further requirements include:
1. Channel assignments, keys for encryption/decryption, and other secure communications are sent to via the narrow band modem connection. In practice, this requirement will provide a separate physical path from the path 216 used for data communications. This provides an extra level of security needed for single user data units retrieving sensitive information (e.g., stock quotes, telecommuting to corporate networks).
2. Informing each RLA to listen to the channel to which it is assigned. In a generic IP router, this task can be accomplished by simply broadcasting on all channels a command to tune a specific RLA to its respective assigned channel. Since the generic router approach uses the same physical path to tune the RLAs as the one in which data is transmitted, here is an inherent security problem. System 200 according to the present invention envisions the use of the narrow band connection - which would be a separate physical or logical medium from the path carrying data transmissions - to tune each of the RLAs. One embodiment of the invention has the narrow band connection connected directly to the service provider, which negates the ability of a generic IP router ability to go directly through the service provider narrow band connection to tune the RLA. Each of the data service providers has a respective application program interface that is used by the present invention to pass channel assignment data from the bandwidth manager 240 over the narrow band connection to perform the RLA channel tuning as part of service negotiation process.
3. Keeping records of the channel bandwidth requests for purposes of billing, traffic measurements, and bandwidth management.
4. Providing admission control to ensure that only authorized information is sent over the channels to the single user data units. In the IP world, anyone who has knowledge of the destination address can send unwanted and unwarranted messages.
5. Maintaining quality of service by limiting the active users of any one channel to a pre-defined maximum level of channel bandwidth utilization or limiting the number of active users of any one channel to a pre-defined maximum number.
Routing, load balancing across channels, collection of traffic measurements, and encryption for secure communications are part of the multiplexing platform unit 210. On the other hand, limiting the number of users per channel to optimize use of channel bandwidth or to maintain quality of service, and to use loading and traffic data to bill the data service provider requires sophisticated data base management work. Experience suggests that decoupling of management functions can result in better performance for the multiplexing platform unit 210. Further, deploying a regional bandwidth manager 240 to control several multiplexing platforms (not shown) allows the benefits of the economies of scale. In this context, a bandwidth manager 240 will perform data service negotiation, billing of the service provider, end user data base management, admission control to maintain quality of service, passing the channel assignment and encryption keys (via the service entity providing the channel assignment and encrypted data), and necessary network management functions. Thus, the bandwidth manager performs many tasks while also managing the available bandwidth on each of the channels that ultimately deliver the data services.
Thus, it will now be understood that there has been disclosed a new apparatus and method for distributing data services from data service providers. While the invention has been particularly illustrated and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form, details, and applications may be made therein. For example, Although plural data service providers are shown in FIG. 2, the present invention would work just as well with only one data service provider.

Claims

An apparatus for delivering data services including a network (204) for communicating data packets according to the internet protocol, a local network unit (210) connected to said network, a plurality of single user data units (220) connected to said local network unit for receiving data packets, each of said single user data units having a unique address, a plurality of data service provider units (300), each of said data service provider units being connected to said network for transmitting data packets to said single user data units via said local network unit, each of said data service provider units being also connected to each single user data unit to which it is adapted to transmit said data packets via another communication path (232) for controlling said transmission of data packets, the apparatus CHARACTERIZED IN THAT:

said local network unit is connected to a plurality of separate broadband channels (212, 213, 214) for multiplexing data packets from said network upon a cable (216) that carries the different broadband channels;

said plurality of single user data units are connected to said local network unit via the plurality of broadband channels;

said local network unit is adapted to operate the broadband channels as part of one sub-network rather than using an independent sub-network for each broadband channel; and in that said apparatus includes

a bandwidth manager (240) connected to said plurality of data service provider units and said local network unit via said network, said bandwidth manager being adapted to keep a dynamic record of an amount of bandwidth used of each of said plurality of broadband channels and to assign any new bandwidth allocation for data services to the broadband channel which has the most bandwidth available.
The apparatus of claim 1, wherein said bandwidth manager is adapted to increment the dynamic record for each amount of bandwidth that is allocated from a channel at the time of a request to deliver data, and to decrement for each amount of bandwidth of a channel that is freed up after all data packets related to the request have been delivered to the respective single user data unit.
The apparatus of claim 1, wherein said local network unit is adapted to maintain a routing table that specifies the single user data unit address and a channel modulator adapted to modulate information received from the data service provider units on a broadband channel to provide data packet routing to a destination user.
The apparatus of claim 3, comprising a channel modulator for each of the broadband channels.
The apparatus of claim 4, further comprising a remote link adapter connected between at least one of said single user data units and said local network unit to demodulate data packets modulated on one of said plurality of broadband channels and convert a format of the demodulated data packets to be compatible with IEEE 802.2.
The apparatus of claim 5, wherein the modulator is adapted to modulate the data packets within each broadband channel using frequency and bandwidth compatible with transmission equipment used for transmission of broadcast television signals.
The apparatus of claim 1, wherein said other communication path for controlling said communication of data packets is bi-directional.
The apparatus of claim 1, wherein said dynamic record keeps a record of each amount of bandwidth that is allocated from a channel at the time of a request to deliver data, and also of each amount of bandwidth that is freed up after all packets related to the request have been delivered.
A method for delivering data services including receiving data packets according to the internet protocol from a first network (300) and multiplexing said data packets by a local network unit (210) onto a second network, receiving said data packets by a plurality of single user data units (220) that are connected to said second network, distributing data packets from a plurality of data service provider units to said single user data units via said first network, said local network unit and said second network, controlling said distributing of data packets from each of said data service provider units to each single user data unit to which it transmits said data packets via another communication path (232) outside of said first network,
CHARACTERIZED IN THAT:

multiplexing by said second network said data packets upon a cable (216) that carries a plurality of different broadband channels (212, 213, 214) connecting said plurality of single user data units to said local network ; and in that said method includes:

operating, by said local network unit, the broadband channels as one subnetwork rather than using an independent sub-network for each broadband channel;

dynamically managing said broadband channels with a bandwidth manager (240) that is connected to said plurality of data service provider units and said local 10 network unit via said network, generating a dynamic record of an amount of bandwidth used of each of said plurality of broadband channels and using this record to fulfill any new bandwidth request for data services to the broadband channel which has the most bandwidth available.
The method of claim 9, further comprising the step of using the record to 15 bill the respective user according to the amount of bandwidth used.